1. Field of the Invention
The present invention relates to a rotor of a rotary electric machine, and particularly to a cooling structure thereof.
2. Description of Related Art
A rotor of a rotary electric machine, described in Japanese Patent Application Publication No. 2006-67777 (JP 2006-67777 A), is configured such that a cooling oil is supplied from a rotor shaft to a plurality of cooling oil passages formed in a rotor core so as to cool down magnets, and then, the cooling oil is discharged to a gap between a rotor outer peripheral surface and a stator.
In JP 2006-67777 A, each of the plurality of cooling oil passages contributes to cooling of the magnets. However, cooling oil passage outlets to the gap between the rotor outer peripheral surface and the stator are formed at several parts in an axial direction, so that the cooling oil flows out into the gap through the several parts in the axial direction. In a region sandwiched between the cooling oil passage outlets in the axial direction, cooling oils from the cooling oil passage outlets interfere with each other, so that the cooling oils are easy to be retained therein. As a result, the cooling oil retained in the gap serves as a rotational resistance to the rotor, which increases a drag loss.